Many industries, especially aerospace, energy, and automotive, extensively use composite fabrics because of its strength, damage resistance, and light weight. However, industries are looking to improve delamination resistance while keeping weight and manufacturing costs low. This invention addresses both issues.
The invention, however, may be limited by its patentable scope. People have used weaved and braided fabrics for over 7,000 years, so there is a significant amount of prior art. This invention combines a triaxial (non-orthogonal), laminates, and integrated interlocking inter-laminar yarns into a composite reinforcement. This composite reinforcement can be used in combination with a polymer matrix.
Engineers increasingly use fiber-reinforced composite materials, particularly for automotive, marine, and armor designs, because of high stiffness and strength with low density. Engineers can also tailor the materials' orthotropic properties to specific applications where certain properties are required in only particular directions of a structure.
It is known to employ prepreg composites with stacked material layers (see FIGS. 1A-1D). Each layer typically has resin and fibers, with the fibers being oriented at, for example, any combinations of 45°/0°, 0°/90°, 30°/90°, 60°/90°, 30°/60°, or 90°/0° for relative adjacent layers. Such conventional fiber patterns, however, are prone to severe delamination, cracking and fiber breakage upon projectile impact. To overcome these problems, fibers have been stitched through laminate layers to overcome delamination issues. Unfortunately, needles used to pass through the reinforcement phase can lead to damage or breakage of the fibers in the affected regions. This can reduce the overall strength of the composite structure.
Laminated structures based on stacking composite layers, however, are susceptible to impact loading that causes delamination, which is separation of layers due to breakage of the composite interface. Once delaminated, projectiles can disintegrate the material by displacing the fibers of individual layers. This poor impact resistance restricts composites from many applications, despite many efforts to understand impact response and improve delamination resistance.